The current communication technology is most strikingly characterized in the complexity and time variation of channels of the communication system as well as error codes brought forth thereby. Therefore, automatic repeat request (ARQ) and forward error correcting (FEC) are usually applied at present for error control. ARQ and FEC are technologies for error control by means of error detecting code and error correcting code, respectively. The principle of ARQ is that a receiving terminal feeds back information through reverse channel, so that the transmitting terminal will not stop retransmitting a data packet with the checked error, until the receiving terminal has judged a correct reception; while the principle of FEC is that an error correcting code is coded and sent from the transmitting terminal and decoded by the receiving terminal, so that an error in the codeword is corrected automatically. ARQ has a better correction capability, but requires reverse channel and is weak in real-timing of communication. On the contrary, FEC has good real-timing and its transceiver control system is simple, but the error correcting code is designed under the worst channel condition and therefore coding efficiency is low.
An HARQ system has the advantages of the above two error control methods, wherein the sent error correcting code has certain capabilities of error correcting, and the receiving terminal informs the transmitting terminal of retransmission only in the case where the error correcting capability is exceeded. To some extent, the deficiencies of communication hysteresis in ARQ and decoding complexity in FEC are prevented, so that higher spectrum efficiency is achieved.
TURBO code is applied commonly in the current HARQ mechanism. The TURBO code has the following deficiencies:    1. It is impossible to check it by itself, and it is necessary to add cyclic redundancy check code (CRC) to check bits, which increases the system costs.    2. The decoding is complex so that the amount of caching data is huge, and the iteration number of decoding is limited so that the decoding delay is long, therefore it is not adapted to real-time services.    3. The performance is deficient during the coding and decoding of codes exclusive of short ones.    4. For high-speed downlink transmission services, the processing workloads of the algorithm concentrate on the mobile station, which increases the complexity for carrying out the mobile station, thus the mobile station has high costs and power consumption and short standby time.